Method of production of ethanol amines



Aprifi 18, 1933. E. w. REID ET AL 1,904,013

METHOD OF PRODUCTION OF ETHANOL AMINES Filed Aug. 18, 1927 y z 2 K gATTORNEYS.

' I VENTORS.

ab-(4M6 Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE ERNEST W.REID, OF PITTSBURGH, AND DONALD C. LEWIS, 0F DARMONT, PENNSYL- VANIA,ASSIGNORS TO CARBIDE & CARBON CHEMICALS CORPORATION, A. CORPO- RATION OFNEW YORK METHOD OF PRODUCTION OF ETHANOL AMINES Application filed August18, 1927. Serial No. 213,890.

C2H4O C2H5ONH2 20 53 0 NH;, (C H O) NH 30211 0 (C2H5O)3N These productshave the following physical properties Boiling point g Monoethanol amine171 C. at 757 mm 1.022 Diethanol amine 270 C. at 748 mm-.- 1.0966Triethanol amine 278 C. at 150 mm.-. 1. 1242 The reaction will proceedwith anhydrous ammonia. and anhydrous ethylene oxide but with almostexplosive violence. It is preferable, therefore, to carry out thereaction in aqueous solution in order that the conditions may becontrolled.

The tendency of the reaction is to produce the triethanol amine. Weprefer to carry out the reaction in such a manner as to result in aproduct composed of approximately 25% diethanol amine and 75% triethanolamine. This mixture has been found to be more useful in the arts than aunitary product. It is useful for causing. the deeper penetration ofdyes on cotton, silk or cellulose fibers and also for securing a deeperpenetration of creosote oil in preserving wood. Other uses for thismixture will be evident to those skilled in the art, such as themanufacture of rubber accelerators, preparation of hydrocarbon-solublesoaps, tanning of leather,

preparation of artificial leather and the siztube sheets.

into the shell outside the porous tubes a cooling medium. While we mayuse any type of heat interchanger, we have, for conveniencc, shown atype in which the cooling medium passes through a nest of tubes, thefluid to be cooled passing outside the tubes. Baiiles 12 may be employedif desired to secure a'greater cooling effect. A circulating pump letforces an aqueous solution of ammonia through the heat int-erchanger.

r The means for introducing the ethylene oxide into the ammonia solutionmay take various forms. We have found that a suitable method is todiffuse the ethylene oxide through porous tubes or plates. In thedrawing we show a device employing this method, said device consistingof a shell 15, having tube-sheets 17 at the ends thereof. Suitableheaders 18-18 are provided for connecting the device with thecirculating pump and a conduit 21 leading from the heat interchanger.Porous tubes 16 extend between the The ethylene oxide is forced throughan opening 19. p

A still 23 is provided in the system on the delivery side of thecirculating pump. I This still may be heated by any suitable means butwe prefer to use steam coils 24. The vapor from the still consisting ofammonia and steam, is collected in any suitable manner and led by aconduit 25 to a tank 26 containing water which absorbs the ammonia.After enough ammonia has been absorbed it may be transferred, eitherwith or without further treatment, to an ammonia supply tank.

The process may be carried out as follows:

The pump being started, the valve from the ammonia supply tank is openedand the system is filled with a solution of ammonia.

At the same time ethylene oxide is forced under pressure into thev shell15 surrounding the porous tubes 16. The ethylene oxide graduallydiffuses through the tubes and combines with the ammonia to form ethanolamines. The solution thus treated is circulated through the closedcircuit by means of thecirculating pump 14 and is cooled in theinterchanger. The ethylene oxide is added at such a rate as to maintainthe temperature of the solution below 50 0., preferably at ethanolamine.

about 40 C. Theamount of oxide added depends upon the product desired.If, for example, 50% of. the theoretical quantity of oxide fortriethanol' amine is-added, that is to say, ethylene oxide in an amountequal to piroduct will be only the triethanol amine.

y using less than 50% of the oxide the final product will contain moreof the monoethanol and diethanol amines and less of the tri- We do notconsider it desirable to use the theoretical quantity of ethylene oxideas we have found that in this case undesirable by-product-s are formedwhich are difficult to remove. We prefer to operate the processes attemperature of between 40 C., and 50 (3., although we have found thatthe reaction will progress at temperatures as lowas 0 C., and as high as100 C. However, at these extreme temperatures the reaction is moredifiicult to control and is usually attended by undesirable by-products.The circulation of the liquid medium is de sirable in' order to preventlocalized overheating at the point of contact betweenthe gas and liquid.When the desired amount of oxide has been added valve 27 is opened andthe solution is transferred to the still 23 in which excess ammonia andwater is removed by distillation, the ammonia evolved duringdistillation being absorbed in water in the tank 26 and therebyrecovered for further use. I

While we have described a method in which the gaseous ethylene oxide isdifiused into an aqueous solution of ammonia, this reaction may becarried out by adding anhydrous ammonia to an aqueous solution ofethylene oxide or both the ethylene oxide and anhydrous ammonia may beadded to water.

We claim:

1. In the process of making ethanolamine involving the operations ofreacting ethylene oxide with an excess of aqueous ammonia while coolingand agitating the mixture, the improvements which consist in graduallyadding the ethylene oxide to the aqueous ammonia by difi'using theformer into the latter at such a rate that the concentration ofuncombined ethylene oxide in the resulting reaction mixture is at alltimes low with respect to the concentration of uncombined ammoniawhereby to minimize the formation of by-products in said reactionmixture, and continuously abstracting heat from said reaction mixturewhereby to maintain the latter at a temperature below 100 C.

2. The improved processes defined in' claim 1, characterized in that thetotal amount of ethylene oxide added equals from about 1.5 to about 2.4times the total quantity of ammonia employed.

3. In the process of making ethanolamines involvin the operations ofreacting ethylene oxide wlth-an excess of aqueous ammonia while coolingand a tating the mixture, the improvements whic consist in graduallyadding the ethylene oxide to the aqueous ammonia by diffusing 'theformerinto a flowing stream of the latter at such a rate that-theconcentration of uncombined ethylene oxide in the resulting reactionmixture is at all times low with respect to the concentration ofuncombined ammonia whereby to minimize the formation of by-products insaid reaction mixture, the total amount of ethylene oxide so addedequalling from about 1.5 to about 2.4 times the total quantity ofammonia employed, while continuously abstracting heat from said reactionmixture whereby to maintain the latter at a temperature not greater thanabout 50 C.

In testimony whereof, we aflix our signatures. I

ERNEST W'. REID. 'DONALD LEWIS.

CERTIFICATE OF CORRECTION.

Patent No. 1,904,013. April 18, 1933.

ERNEST W. REID, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,line 4, beginning with the words that is" strike out all to andincluding "present," in line 7; lines 10 to 13, strike out the words "inother words, ethylene oxide may be added in an amount epual to fromabout 1.5 to about 2.4 times the total I quantity of ammonia present."and insert the same after "amine." in line 15; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the ease in the Patent Office.

Signed and sealed this 19th day of June, A. D. 1934.

Bryan M. Battey (Seal) Acting Commissioner of Patents.

